Apparatus for handling sheets on a rotary copying cylinder

ABSTRACT

A rotary cylinder for handling sheets in copying operations is provided with a clamping bar which is reciprocable in and out relative to a slot in the circumferential wall of the cylinder and as the cylinder is rotated is moved successively (1) outward to receive the leading edge of a sheet, (2) inward to clamp the sheet edge against an edge of the slot, (3) then further inward after the copying work on the sheet, so as to release the sheet edge, and (4) finally outward again to eject the sheet edge by pushing it out of the slot if it fails to spring out of its own accord. Simple control means enable steps (3) and (4) to be performed in any desired relationship to one or more rotations of the cylinder.

United States Patent [1 1 Bongers 11 3,744,791 July 10,1973

[ APPARATUS FOR HANDLING SHEETS ON A ROTARY COPYING CYLINDER [75] Inventor: Andreas M. G. Bongers, Blerick,

Netherlands [73] Assignee: Oce-van der Grinten N.V., Venlo,

Netherlands [22] Filed: July 8, 1971 [21] Appl. No.: 160,620

[52] US. Cl. 271/80, 101/409 [51] Int. Cl B411 l/30, B65h 29/20 [58] Field of Search 271/51, 80, 82-83;

[5 6] References Cited UNITED STATES PATENTS 5/1960 Rossetto 101/409 X' Primary Examiner-Edward A. Sroka Att0rneyAlbert C. Johnston [57] ABSTRACT A rotary cylinder for handling sheets in copying operations is provided with a clamping bar which is reciprocable in and out relative to a slot in the circumferential wall of the cylinder and as the cylinder is rotated is moved successively (l) outward to receive the leading edge of a sheet, (2) inward to clamp the sheet edge against an edge of the slot, (3) then further inward after the copying work on the sheet, so as to release the sheet edge, and (4) finally outward again to eject the sheet edge by pushing it out of the slot if it fails to spring out of its own accord. Simple control means enable steps (3) and (4) to be performed in any desired relationship to one or more rotations of the cylinder.

8 Claims, 8 Drawing Figures Pmzmwm 3.144.191

. SHEU 1. BF 3 INVENTOR.

ANDRE/{5 me. eolveeas BY ATTORNEY PAIENIEDJUL 1 0191s 3 744,791

SHEEI 2 BF 3 INVENTOR. A N DR EA 5 MG. BONGERS A T mmy APPARATUS FOR HANDLING SHEETS ON A ROTARY COPYING CYLINDER This invention relates to a method and apparatus for handling sheets on a rotary copying cylinder of the type provided with a clamping bar movable in a slot of the cylinder and with means for moving the clamping bar from an initial position in which it protrudes beyond the cylinder for picking up the leading edge of a sheet or the like to be used during the copying process, to a retracted position in which said edge is gripped between a part of the clamping bar and a side wall of the slot.

In known copying cylinders equipped with clamping devices of this kind the clamping bar can be moved be tween two positions. In one of these positions it clamps the edge of a sheet against the slot. In the other position it protrudes beyond the cylinder so that the sheet clamped can be removed and a new sheet fed to the cylinder.

When a cylinder so equipped handles sheets that adhere strongly to its surface, e.g. because of static electricity, or that tend to curl, e.g. because of the cylinder being heated, it may occur that when the clamp has opened the edge of the sheetis not released from but continues rotating with the cylinder, thus preventing the introduction of a new sheet.

To obviate such difficulties apparatus of this kind is usually provided with means which, when the clamping device has opened, will exert a force causing the edge of the clamped sheet to be pushed out of the clamp and away from the cylinder. Such means are known by which a friction force is exerted on the sheet opposite to the direction of movement of the cylinder; or an air current is induced to release the edge from the cylinder by suction or by blowing; or scrapers are slid on the cylinder surface after the clamp has opened, to remove the sheet from the cylinder. In another known technique the cylinder is provided with means operated simultaneously with and possibly even by the clamping device, which, e.g. by passing through the wall of the cylinder, push against the front edge of the sheet so as to displace it from the cylinder to a location outside the range of action of the clamp.

However, the known kinds of such edge removing means make the apparatus so complicated that it is no longer attractive for use as a simple copying cylinder.

The object of the present invention is to provide a technically simpler solution of the problem of assuring the desired immediate release and ejection of the sheet from the copying cylinder.

According to the invention, this object is attained by moving a clamping bar to a position in which an edge clamping part thereof is situated further to the inside of the cylinder than the clamped edge of the sheet, thus freeing that edge of the sheet, after which the clamping bar is moved back to the initial position so that during this movement its upper (outer) edge portion pushes the edge of the sheet out of the slot in the cylinder if the edge has not yet jumped entirely out of the slot of its own accord.

In this way the clamping bar serves not only to clamp the edge of the sheet but also to remove it from the slot after it has been released, so that no complicated auxiliary means are necessary.

The invention can be applied to cylinders that clamp a sheet only during partial revolution, such as is the case e.g. with the counterpressure cylinder in offset printers.

The invention is also useful where a sheet must be retained on the cylinder during a number of revolutions, such as is the case e.g. when an original of which a number of prints is to be made is secured to the glass cylinder of a light-printing machine, or when an offset plate is clamped on the plate cylinder of an offset printer. To achieve the intended operation in the lastmentioned cases, the movement of the clamping bar and of course also its control are to be adapted to the operating needs. This adaptation can be effected in various ways.

According to an advantageous embodiment of the invention, a highly automatized control of the operation is obtained by an arrangement in which the clamping bar is provided with at least one cam coacting with at least two cam guides for moving the clamping bar. The cam guides and cam are displaceable one relative to the other in the axial direction of the cylinder, so that one or the other of the two guides will engage with and position the cam. One cam guide is made circular with such a radius that it will keep the cam and the clamping bar continuously in the position in which a sheet is clamped to the cylinder. The other cam guide is made non-circular, with an effective radius which along one circumferential part of the guide is smaller and along another circumferential part thereof is larger than the effective radius of the circular guide so that, when the cylinder rotates with the cam engaging the non-circular guide, components of movement are produced by which the clamping bar is successively brought into the positions for picking up, clamping, re leasing and ejecting a sheet.

The foregoing and other features and advantages of the invention will be further evident from the following detailed description and the accompanying drawings of illustrative embodiments.

In the drawings:

FIGS. 1, 2, 3 and 4 are schematic views of the various working positions of the clamping bar of a copying cylinder embodying the invention;

FIGS. 5 and 6 are schematic views of other embodiments of clamping bars suitable for the'functions of the invention; and

FIGS. 7 and 8 schematically represent, partially by cross-sections, means suitable for controlling the movements of the clamping bar.

FIGS. 1-4 show a rotary copying cylinder which comprises a cylindrical peripheral wall 1 having its ends closed by end walls or flanges 2. A radial slot is provided in the walls 1 and 2 to receive a clamping bar 4 mounted for sliding movement in the slot. This clamping bar is provided with cam followers 5 protruding beyond end walls of the cylinder, which followers engage, and are positioned radially relative to the cylindrical wall 1 by, cam guides or tracks 6 mounted e.g. on frame plates situated adjacent to the ends of the cylinder.

The copying cylinder is rotated by any suitable means in known manner. As it rotates, the clamping bar 4 is moved radially outwardly and inwardly (up and down as viewed in the drawings) in the slot 3 as a result of the coaction between the cam followers 5 and the guides In the condition shown in FIG. 1 the clamping bar occupies an outward position in which its notched end 7 protrudes outside the cylinder to function as a sheet clamping member. In this position the leading edge of a sheet 8 being transported along a table 11 by feed rollers 9 and is received in the open notch of the protruding end of the clamping bar. Upon rotation of the copying cylinder beyond that sheet receiving position with corresponding forward movement of the sheet 8, the clamping bar 4 is drawn radially inwardly in the slot 3 to a clamping position as shown in FIG. 2, as a result of which the leading edge of sheet 8 is pressed into the slot 3 and is clamped therein between the backward edge of the slot formed along cylinder wall 1 and the outer portion of the notched bar end or clamping member 7.

The sheet 8 is thus firmly clamped to the surface of the cylinder and, upon further rotation of the cylinder, it can be subjected to a copying operation. The copying operation may be, for example, a printing operation effected with the aid of a printing roller 12, or it may involve any of various other operations such, for example, as exposure to light or other radiation, spraying, heating, etc., depending upon the copying process being used.

After the copying operation, upon rotation of the cylinder to the further position thereof shown in FIG. 3, the clamping bar is drawn so deeply into the slot 3 that its edge clamping end is located farther to the inside of the cylinder than the clamped edge of the sheet 8. The edge of the sheet is thus freed from constraint by the clamping bar, and due to its own elasticity it will jump slightly away from the adjacent edge of wall 1. Then, upon further rotation of the cylinder to a position as shown in FIG. 4, the clamping bar 4 is moved again to its outward position in which the notched end 7 protrudes out of the slot, and the edge of the sheet thus is pushed out of the slot by the end of the clamping member and displaced away from the cylinder.

If the copying work being done requires the sheet to be released after one or more full revolutions of the cylinder, this manner of operation can be obtained, for example, by forming the cam guide 6 on a support that can be caused to rotate with the cylinder or stopped according to the required program.

In the embodiment of FIGS. 1-4 the slot in which the clamping bar 4 is moved is radially directed and the leading edge of the clamped sheet is folded at an angle of approximately 90. It will be apparent, however, that the slot can also be slanted relative to a radius of the cylinder, for example, as shown at 3a in FIG. 5, and the clamping bar 4a may have its notched end 7a modified correspondingly, in order that the leading edge of the clamped sheet will be folded at a smaller angle.

Instead of being arranged for longitudinal sliding movement in a slot of the cylinder, the clamping bar can be arranged for swinging movement in a cut-out area or slot of the cylindrical wall 1 of the copying cylinder. An example of such a modification is shown schematically in FIG. 6, in which clamping bar 4b is mounted for swinging movement about axis 3b and the notched forward edge 7b of this bar coacts with an arcuate surface 70 provided along the adjacent edge of the cut-out area or slot.

According to the embodiment of FIGS. 7 and 8, the copying cylinder 1 is supported rotatably through bearings 13 on a shaft 12 and is rotated by a drive unit, not shown, engaging with gear 14 secured to an end of the cylinder. A clamping bar 4, such as that of FIGS. l-4, is provided. with shaft ends 15 protruding outside the cylinder, on which ends cam wheels 16 are mounted rotatably in bearings.

An assembly of two adjacent cam guides 18 and 19 is mounted on a bushing 17 for axial sliding movement on shaft 12. This assembly is connected to a yoke 20, the legs of which pass through a frame 21 that supports the shaft 12 and thus the cylinder thereon. Yoke 20 is connected to a tension spring 22 and also, by means of an arm 23 and a lever 25 supported by a pivot pin 24, to the core 26 of a solenoid 27.

When solenoid 27 is energized, its core 26 is drawn into its body and thus the yoke and the cam guides are held in a position in which the cam wheel 16 bears against and is positioned by cam guide 18. A tension spring 28 keeps wheel 16 pressed against guide 18. In this condition, and with cylinder 1 rotating, the clamping bar 4 is moved radially in the slot 3 of the cylinder in the manner described above in reference to FIGS. 1-4.

If solenoid 27 is not energized, or when it is deenergized, the yoke 20 and cam guides 18 and 19 are moved by spring 22 to the left as viewed in FIG. 7, to a position in which the cam wheel 16 engages and is positioned by the circular cam guide 19. In that condition of the apparatus, the guide 19 maintains the clamping bar 4 in a position in which the leading edge of a sheet is kept clamped in the slot of the rotating cylinder, in accordance with the operating condition illustrated in FIG. 2. After the sheet so held to the cylinder has been processed to the required extent, energization of the solenoid will cause the cam guide 18 to be shifted back into engagement with cam wheel 16, whereupon a descending chordal portion of guide 18 (FIG. 8) will cause the clamping bar to be retracted into the slot 3, so as to release the clamped sheet edge according to FIG. 3, and then an ascending chordal portion of guide 18 will cause the bar end 7 to eject the freed sheet edge from the cylinder according to FIG. 4.

It is to be understood that the foregoing description and the accompanying drawings are illustrative only and that the invention may be carried out in other ways while still utilizing its new features, which are intended to be defined by the appended claims.v

What is claimed is:

1. Apparatus for handling sheets on a rotary copying cylinder having a slot extending axially in its circumferential wall, a clamping bar reciprocable in said slot, said bar having a sheet receiving edge portion, and means operable by rotation of the cylinder to move said bar to an initial position in which said edge portion protrudes from said slot to receive the leading edge of a sheet fed thereto and then to retract said bar so as to draw said edge into said slot and clamp it between said edge portion and a margin of said slot, thus holding the sheet to the surface of the cylinder during a copying operation, comprising means operable by further rotation of the cylinder after the copying operation for moving said bar farther into the cylinder to a position therein in which said edge of the sheet is released from constraint by said edge portion and then moving said bar outward and thus by said edge portion pushing said edge out of said slot if it has not sprung out of its own accord.

2. Apparatus according to claim 1, said circumferential wall having substantially parallel confronting surfaces extending therethrough and forming margins of said slot, said bar lying parallel to said surfaces and being slidable rectilinearly in said slot, said sheet receiving edge portion comprising a notch formed in and axially along a side of the outer part of said bar and being sufficiently wide outside said notch to fill all the space between said surfaces except the part thereof required for the drawing in and clamping of said leading edge.

3. Apparatus according to claim 2, the center line of said slot and said bar lying substantially on a radius of said cylinder.

4. Apparatus according to claim 2, the center line of said slot and said bar lying at an inclination to a radius of said cylinder.

5. Apparatus according to claim 1, said bar being pivotally mounted along a backward portion thereof away from said sheet receiving edge portion for swinging movement of the latter outwardly and inwardly relative to said margin of said slot, said edge portion comprising a notch formed in and axially along a forward edge of said bar, said margin being formed by an arcuate surface lying adjacent to the path of swinging movement of said edge portion with only enough space therebetween for the drawing in and clamping of said leading edge.

6. Apparatus according to claim 1, further comprising control means for rendering the last recited means inactive and maintaining said bar in the sheet clamping position thereof during any selected extent of rotation of said cylinder and for thereafter activating said last recited means.

7. Apparatus according to claim 6, said last recited means including cam follower means fixed to and rotated with said bar and first cam guide'means engageable by said follower means for positioning and displacing the same and said bar as said cylinder is rotated, said control means comprising second cam guide means engageable by said follower means for maintaining said bar in the sheet-clamping position thereof as' said guide means.

Patent No. 3,744,791 Dated July 1% 1973 Andreas M. G. Bongers Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the tower sheet insert [30] Foreign Application Priority Data July 16, 1970, Netherlands 70.10519 Signed and sealed this 20th day of August 1974.

(SEAL) Attest:

MCCOY M. GIBSON; JR. C. MARSHALL- DANN Attesting Office-r 1 Commissioner of Patents FORM PC4050 uscoMM-oc 60876-P69 i U75. GOVIINNENY PRINTING OFFICE I"! O-Jii-SJL 

1. Apparatus for handling sheets on a rotary copying cylinder having a slot extending axially in its circumferential wall, a clamping bar reciprocable in said slot, said bar having a sheet receiving edge portion, and means operable by rotation of the cylinder to move said bar to an initial position in which said edge portion protrudes from said slot to receive the leading edge of a sheet fed thereto and then to retract said bar so as to draw said edge into said slot and clamp it between said edge portion and a margin of said slot, thus holding the sheet to the surface of the cylinder during a copying operation, comprising means operable by further rotation of the cylinder after the copying operation for moving said bar farther into the cylinder to a position therein in which said edge of the sheet is released from constraint by said edge portion and then moving said bar outward and thus by said edge portion pushing said edge out of said slot if it has not sprung out of its own accord.
 2. Apparatus according to claim 1, said circumferential wall having substantially parallel confronting surfaces extending therethrough and forming margins of said slot, said bar lying parallel to said surfaces and being slidable rectilinearly in said slot, said sheet receiving edge portion comprising a notch formed in and axially along a side of the outer part of said bar and being sufficiently wide outside said notch to fill all the space between said surfaces except the part thereof required for the drawing in and clamping of said leading edge.
 3. Apparatus according to claim 2, the center line of said slot and said bar lying substantially on a radius of said cylinder.
 4. Apparatus according to claim 2, the center line of said slot and said bar lying at an inclination to a radius of said cylinder.
 5. Apparatus according to claim 1, said bar being pivotally mounted along a backward portion thereof away from said sheet receiving edge portion for swinging movement of the latter outwardly and inwardly relative to said margin of said slot, said edge portion comprising a notch formed in and axially along a forward edge of said bar, said margin being formed by an arcuate surface lying adjacent to the pAth of swinging movement of said edge portion with only enough space therebetween for the drawing in and clamping of said leading edge.
 6. Apparatus according to claim 1, further comprising control means for rendering the last recited means inactive and maintaining said bar in the sheet clamping position thereof during any selected extent of rotation of said cylinder and for thereafter activating said last recited means.
 7. Apparatus according to claim 6, said last recited means including cam follower means fixed to and rotated with said bar and first cam guide means engageable by said follower means for positioning and displacing the same and said bar as said cylinder is rotated, said control means comprising second cam guide means engageable by said follower means for maintaining said bar in the sheet-clamping position thereof as said cylinder is rotated and means for selectively bringing either said first cam guide means or said second cam guide means into working engagement with said cam follower means.
 8. Apparatus according to claim 7, said first and second cam guide means being disposed adjacent to each other beyond said cylinder about the axis thereof, and said cam follower means and said cam guide means being relatively displaceable along said axis so as to move said follower means selectively out of engagement with one and into engagement with the other of said guide means. 